The present invention relates to a vehicular headlamp. More specifically, the invention relates to a headlamp having improved long-distance visibility in right and left diffused-beam areas without dazzling the vision of drivers of oncoming vehicles.
FIG. 6 shows a light distribution pattern obtained from a vehicular headlamp according to the conventional practice radiated onto a screen disposed in front of the vehicle. In FIG. 6, Hxe2x80x94H notes a horizontal line and that Vxe2x80x94V denotes a vertical line extending perpendicularly to the horizontal line Hxe2x80x94H.
The low beam of the headlamp, used when approaching an oncoming vehicle or driving in a city area, forms a light distribution pattern a. A horizontal cut line b, defining an upper boundary of the light distribution pattern a, generally assumes the shape of flattened xe2x80x9cZxe2x80x9d. The horizontal cut line b is located below the horizontal line Hxe2x80x94H on the side of the opposite lane with respect to the vertical line Vxe2x80x94V (i.e., on the right side in countries where vehicles are required by law to keep to the left). The horizontal cut line b on the side of one""s own lane (i.e., on the left side in those countries) is located above the line on the side of the opposite lane. By shaping the horizontal cut line b as described above, it is possible to effectively illuminate one""s own lane without dazzling drivers of oncoming vehicles or pedestrians. In countries where vehicles are required to keep to the right, the cut line b is of course located on the left side of the vertical line Vxe2x80x94V.
The horizontal cut line b of the light distribution pattern of a low beam emitted from the aforementioned vehicular headlamp according to the conventional practice differs in height when viewed in the lateral direction, but extends horizontally as a whole. For this reason, the aforementioned vehicular headlamp is confronted by a problem of insufficient long-distance visibility.
Concerning the opposite lane, it is obviously necessary to set the horizontal cut line b so as to prevent the vision of drivers of oncoming vehicles from being dazzled. However, as far as illumination of an area outside one""s own lane or the opposite lane is concerned, light should be radiated in a region extending above the horizontal cut line b in right and left diffused-beam areas of the light distribution pattern a so as, for example, to improve visibility far ahead of one""s own vehicle when driving along a leftward curve (in the case where vehicles are required by law to keep to the left) so as to allow the driver to better see pedestrians to the side of the road far ahead and well in advance.
The present invention has been made in consideration of the aforementioned circumstances. It is an object of the present invention to provide a headlamp having improved long-distance visibility in right and left diffused-beam areas without dazzling drivers of oncoming vehicles.
In order to achieve the above and other objects, the present invention provides a vehicular headlamp comprising a light source, a reflector for radiating light emitted from the light source forwards, and a cover lens for covering an area in front of the reflector and the light source, wherein a light distribution pattern of a low beam emitted from the vehicular headlamp has a horizontal cut line at least on the side of the opposite lane, and wherein long-distance visibility enhancing portions extending above the horizontal cut line of the light distribution pattern are formed in end portions of the horizontal cut line.
Thus, the vehicular headlamp according to the present invention offers improved visibility of a distant range by means of the long-distance visibility enhancing portions extending above the horizontal cut line of the light distribution pattern, thus allowing the driver, for example, to better see pedestrians standing ahead in one""s own lane along a curved road, or pedestrians standing outside either lane well before a dangerous situation could develop.
The long-distance visibility enhancing portions extending above the horizontal cut line of the light distribution pattern can be formed in different ways, including:
(1) a vehicular headlamp having a reflector for reflecting and condensing light emitted from a light source, a projection lens for projecting the light reflected by the reflector forwards, and a shade having an upper edge defining a horizontal cut line, wherein downward-extending portions extending further downwards than other portions are formed in right and left end portions of the upper edge of the shade, and wherein the long-distance visibility enhancing portions of a light distribution pattern are formed by the downward-extending portions of the shade;
(2) a vehicular headlamp having a stepped reflector with its entire reflecting surface divided into small reflecting sections, each of which distributes light emitted from the light source to a predetermined position so as to form a predetermined light distribution pattern, wherein light reflected by some of the reflecting sections of the stepped reflector form the long-distance visibility enhancing portions of the light distribution pattern; and
(3) a vehicular headlamp wherein a control portion formed in the cover lens directs some of the light reflected by the reflector to form the long-distance visibility enhancing portions.